The satisfaction level of the Big Four banks' personal customers in the six months to October 2016 was 79.5 per cent, according to Roy Morgan Research, based on a sample of more than 25,000 bank customers. While the current month on month difference measured by Roy Morgan was so slight as to be a rounding error between September and October (with satisfaction down by 0.3 percentage points), this level represents a two percentage point decline in satisfaction with the Big Four since May 2015, when it peaked at 81.5 per cent. The main cause of this decline has been the big reduction in satisfaction among home loan customers, down 3.4 per cent points to 75.8 per cent, compared with a decline of only 0.9 per cent to 80.4 per cent for other customers.In October, the NAB was the only bank among the Big Four to show an improvement in satisfaction (up 0.7 per cent to 78.7 per cent) and as a result it moved past the ANZ (78.1 per cent) into second place behind the CBA (81.7 per cent). NAB's improvement was due to increased satisfaction among "non home loan" customers (up 0.9 per cent points), whereas home loan customer satisfaction declined (down 0.3 per cent points).The largest decline in satisfaction among the Big Four in October was among ANZ customers (down 0.7 per cent points to 78.1 per cent), the result of a drop in satisfaction among non-home loan customers (down 1.3 per cent points). Despite very low interest rates that should favour borrowers rather than depositors, home loan customers have lower satisfaction than other customers for all four of the major banks. The reverse is the case with the remaining top ten largest banks. Home-loan customers have higher satisfaction for Bendigo Bank, Bank SA, ING Direct, ME Bank and St George.The mutual banking sector's overall customer satisfaction was 91.0 per cent in October, well above the Big Four's average (79.5 per cent) and higher than the best performers among the largest ten consumer banks, i.e. Bendigo Bank (89.4 per cent) and ING Direct (89.1 per cent).The best performers among the major mutual banks were Greater Bank (95.4 per cent), Victorian Teachers Mutual Bank (94.9 per cent), Bank Australia (94.4 per cent) and Teachers Mutual Bank (94.0 per cent).Among bank customers, only 29.1 per cent can be regarded as having a 'very high' likelihood of recommending their bank (scoring 9 or ten on a ten point scale). The two best performers among the ten largest banks on this measure are Bendigo Bank (45.6 per cent) and ING Direct (43.5 per cent). Both of these banks are well clear of the other majors, with the Big Four having an average of only 26.6 per cent classified as 'very high' advocates.On average, close to half (49.4 per cent) of the mutual banks' customers are 'very high' advocates.